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From: yee@trident.arc.nasa.gov (Peter E. Yee)
Newsgroups: sci.space.shuttle
Subject: Shuttle Status for 04/22/91 (Forwarded)
Message-ID: <1991Apr22.234907.29805@news.arc.nasa.gov>
Date: 22 Apr 91 23:49:07 GMT
Sender: usenet@news.arc.nasa.gov (USENET Administration)
Organization: NASA Ames Research Center, Moffett Field, CA
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          SPACE SHUTTLE MISSION STS-39 COUNTDOWN STATUS --- April 22, 1991

                                LAUNCH MINUS ONE DAY

               Work at pad 39-A continues to go smoothly today as launch
          team members press toward launch of the Space Shuttle Discovery
          on Mission STS-39 at 7:05 a.m. Tuesday, April 23. The launch
          window extends through 10:31 a.m.

               Mission STS-39 is an unclassified Department of Defense
          mission featuring two primary payloads: Air Force Program 675 and
          the Strategic Defense Initiative's Infrared Background Signature
          Survey. There are also two secondary payloads; Space Test Payload
          and a Multi-Purpose Experiment Canister.

               The countdown clock entered the T-11 hour planned built-in
          hold this morning at 4:45. The clock will continue to hold until
          resuming the count at 4:45 p.m. today.

               Yesterday, the Power Reactant and Storage Distribution
          System on-board storage tanks were serviced with liquid hydrogen
          and liquid oxygen reactants. Following PRSD loading, the orbiter
          midbody umbilical unit was retracted. Communication activation
          checks then commenced at about 9:00 p.m. last night.

               The Rotating Service Structure is scheduled to be moved away
          from the vehicle at 11:45 a.m. today. Also today, final crew
          equipment and time critical items will be stowed on the orbiter.

               At 7:45 tonight the pad will be cleared of all personnel.
          Then at 10:45 p.m., operations will begin to load the external
          tank with liquid hydrogen and liquid oxygen propellants. Tanking
          operations should be completed by 1:45 a.m. Tuesday.

               The seven member STS-39 flight crew, already split into two
          teams to accommodate a 24-hour in-flight work schedule, are today
          undergoing weather and systems briefings. Tomorrow for launch,
          the crew will be awakened at 2:10 a.m. for breakfast. They will
          have a final weather briefing, suit up and at 3:50 a.m. depart
          their crew quarters for pad 39-A.

               The forecast weather for Tuesday's liftoff shows a 60
          percent chance of violating launch constraints at the opening of
          the window. There is a 50 percent chance of violating constraints
          throughout the entire three-hour, 26-minute window. A front
          located through western Florida and into the Gulf could produce
          low clouds and favorable conditions for thundershowers.

               Wednesday's forecast calls for a 40 percent chance of
          violating launch constraints; Thursday's forecast calls for a 30
          percent chance of violation.